4 - Aquatic locomotion

Question 1

In water there is… gravity and … buoyancy than in air

Answer 1

less
more (leading to increase ability to float)

Question 2

Freshwater buoyancy

Answer 2

1000kg/m3

Question 3

Seawater bouyancy

Answer 3

1026kg/m3

Question 4

Air buoyancy

Answer 4

1.18kg/m3

Question 5

What is important for reducing friction & turbulence?

Answer 5

The body shape

Question 6

Forward mvmnt causes?

Answer 6

Frictional drag

Question 7

Why do invertebrates have higher densities than fresh or marine water?

Answer 7

Due to their constituents - proteins and carbohydrates
- makes them less buoyant

Question 8

Mechanisms uses to counteract low or maintain neutral buoyancy

Answer 8

• fats (lower density than proteins)
• Ionic solutions (i.e. salts)
• air

Question 9

Why is the marine copepod Notostomus neutrally buoyant?

Answer 9

Its enlarged carapace contains a low-density body fluid

Question 10

Why is the deep sea squid Helicocranchia neutrally buoyant?

Answer 10

(is a sluggish swimmer)
has a very large body cavity with fluid that reduces the overall density

Question 11

What is best for achieving neutral buoyancy?

Answer 11

Air (only 5-7% air volume is needed for an organism to be buoyant in sea- or fresh-water)

Question 12

Why are air-filled chambers problematic for deep diving?

Answer 12

the hydrostatic pressure associated with increased depth can collapse these chambers

Question 13

Body types for bouynacy

Answer 13

• Air-filled chambers (Cephalopods)
• Rigid-walled gas chamber (cuttlebone)

Question 14

How do rigid-walled gas chambers work?

Answer 14

Maintains gas pressure below the externa hydrostatic pressure

Question 15

Cuttlefish Sepia officinalis attaining neutral buoyancy

Answer 15

• Uses its cuttlebone
• Cuttlebone divided into chambers rigidly supported by lamellae and pillars

Question 16

The volume of gas in the cuttlebone depends on the ?

Answer 16

• hydrostatic pressure (HP) which forces fluids into the cuttlebone and
• osmotic pressure (OP) that withdraws fluid from the cuttlebone due to differences in solutes between the cuttlebone and blood vessels.

Question 17

The underlying epithelium regulates… (Cuttlefish)

Answer 17

the osmotic composition of the fluid that partially fills the chambers

Question 18

Thrust force

Answer 18

‘Force generated by a rotating propeller that enables a vessel to move through the water’

Question 19

Mechanisms that generate thrust force

Answer 19

1. Rowing
2. Oscillation
3. Undulation
4. Jet propulsion

Question 20

Rowing def

Answer 20

(Diving beetles)
The hydrodynamic drag (fluid resistance) from the rowing movements of the rear legs produce forward thrust during the forward phase of swimming

Question 21

Oscillation def

Answer 21

A back and forth movement. Creates a ‘flapping’ movement and can be used to generate lift

Question 22

Undulation def

Answer 22

involves sinusoidal waves passing down the body/a fin/fins. Creates a ‘frilly’ movement that propels the animal forward through the water column.

Question 23

Sinusoidal waves def

Question 24

Jet propulsion def

Answer 24

Thrust can be generated by expelling water from different organs or cavities
Jet propulsion creates the movement of the animal in one direction and is achieved by the expulsion of water in the opposite direction, typically from a specialised cavity

Question 25

Examples of organs or cavities in jet propulsion

Answer 25

• Mantle cavity of a squid
• Rectal chamber of a dragon fly larvae
• Gastrovascular cavity of a jellyfish
• Rapid closing of shells of a bivalve scallop

Question 26

Jet propulsion mechanism in a cephalopod (3)

Answer 26

1. The mantle cavity is first filled with seawater.
2. The squid contracts its muscular mantle to send water out of its siphon (jet orifice). The siphon is highly flexible - it can point in any direction and contract independently of the mantle.
3. Arrows of “swimming direction” and “Jet direction” are opposite to each other!

Question 27

Jet orifice def

Question 28

Why can the siphon point in any direction and contract independently of the mantle?

Answer 28

The siphon is highly flexible

Question 29

A squid with specialized fins

Answer 29

A squid can oscillate and undulate its lateral fins moving them synchronously or independently, to generate lift and create fine manoeuvres.

Question 30

What can fin shape and size provide info on? (squid)

Answer 30

• How they are being used
• Where the species lives in the ocean

Question 31

A mechanically optimal method of swimming with elongated fins has evolved independently at least how many times in both vertebrate and invertebrate swimmers across three different phyla

Answer 31

8 times

Question 32

Madreproite def & function

Answer 32

special skeletal plate – controls opening to exterior

Question 33

Stone canal def

Answer 33

Has ring canals and radial canals (one for each arm)

Question 34

Tiedemann’s bodies def

Answer 34

Coelomocyte production. Part of stone canal

Question 35

Polian vesicles def

Answer 35

pressure regulators. Part of stone canal

Question 36

Lateral canal def

Answer 36

ending in tube foot. Consists of ampullae (hydraulic pressure regulator) and podium (hollow, muscular)

Question 37

Ampulla def

Answer 37

Fluid reservoir used to operate the podium

Question 38

Lateral canal valve

Answer 38

Isolates tube foot from the rest of the system

Question 39

Ampulla method

Answer 39

Ampulla contracts – forces fluid into podium – sucker pressed against surface – adhesion with mucus

Question 40

Podium method

Answer 40

Podium contracts – fluid forced back into ampulla – tube foot released from surface